1. Field
The present invention relates generally to transmit signal leakage. More specifically, the present invention relates to systems, devices, and methods for mitigating the effects of transmit signal leakage in a wireless full-duplex communication system.
2. Background
A wireless device in a wireless full-duplex communication system can simultaneously transmit and receive data for two-way communication. One such full-duplex system is a Code Division Multiple Access (CDMA) system. On a transmit path, a transmitter within the wireless device may modulate data onto a radio-frequency (RF) carrier signal to generate an RF modulated signal and amplify the RF modulated signal to obtain a transmit signal having the proper signal level. The transmit signal may be routed via a duplexer and transmitted from an antenna to one or more base stations. On a receive path, a receiver within the wireless device may obtain a received signal via the antenna and duplexer and amplify, filter, and frequency down-convert the received signal to obtain baseband signals, which are further processed to recover data transmitted by the base station(s).
For a full-duplex wireless device, the RF circuitry in the receiver is often subjected to interference from the transmitter. For example, a portion of the transmit signal typically leaks from the duplexer to the receiver, and the leaked signal (which is commonly referred to as a “transmit leakage” signal or a “transmit signal leakage”) may cause interference to a desired signal within the received signal. Since the transmit signal and the desired signal typically reside in two different frequency bands, the TX leakage signal can normally be filtered out. However, at large transmit signal power levels and using practical small size RF filters, a residual transmit leakage signal may be present at the receiver. Additionally, any transmit leakage signal may interact with a “jammer” (which is a large amplitude undesired signal close in frequency to the desired signal) to generate “cross modulation” distortion components. Distortion components that fall within the signal band of the desired signal and which are not filtered out act as additional noise that may degrade performance.
A need exists for mitigating the effects of transmit signal leakage. More specifically, a need exists for systems, devices, and methods for mitigating the effects of transmit signal leakage in a wireless full-duplex communication system.